Incandescent electricl lamp for series service



p 1 2-9 c. M. RIVELY ETAL 9 9 INCANDESCENT ELECTRIC LAMP FOR SERIES SERVICE Filed June 21, 1947 INVENTQRS 61M. F/VEAZY K POCKEE.

Patented Sept. 20, 1949 INCANDESCENT ELECTRIC LAMP FOR SERIES SERVICE Clair Michael Rively, Bloomfield, and Kenneth G. Crocker, East Orange, N. J., assignors to Westinghouse Electric Corporation, East Pittsburgh, Pa., a corporation of Pennsylvania Application June 21, 1947, Serial No. 756,228,

8 Claims. (Cl. 176-16) This invention relates to incandescent electric lamps particularly adapted for series service, and more especially to a lamp with a device associated with its leads for continuing an electric circuit therethrough in case the filament fails during service.

The principal object of our invention, generally considered, is to provide an incandescent electric lamp with circuit-maintaining means associated with its leads, whereby if the filament breaks while energized during series operation with other lamps, the circuit is maintained without interruption, thereby preventing the associated lamps from being unintentionally ex tinguished.

Another object of our invention is to provide a cut-out feature for use with 30 volt series lamps, whereby such a lamp may be used in a 20'lamp, 600 volt, D. C. circuit, and maintain continuity of the circuit even upon failure of its filament.

A further object of our invention is to provide for spacing the lead wires of a series-service incandescent electric lamp a very short distance, say from .0005" to .003", as by means of a perforated insulator, whereby upon failure during operation of the lamp filament, the circuit through lamps in series therewith is maintained by arcing through the insulator.

A still further object of our invention is to provide for spacing inner portions of leads of an incandescent electric lamp by means of foraminous insulating material, such a small piece of glass ribbon woven from thread .0015" in diameter and held in place by a metal strap properly staked, whereby upon failure of filament, arcing through the interstices occurs and maintains the operation of lamps which may be in series therewith.

Other objects and advantages of the invention will become apparent as the description proceeds.

Referring to the scale drawing:

Figure 1 is an elevational view, full size in the drawing accompanying this application, with parts broken away, of an incandescent electric lamp embodying our invention.

Figure 2 is an enlarged elevational view, with parts in section, of a portion of the mount of such a lamp.

Figure 3 is a further-enlarged horizontal sectional view on the line III-III of Figure 2 in the direction of the arrows.

Figure 4 is an elevational view of a piece of woven glass ribbon which may be employed for spacing the leads of a lamp embodying our invention.

Figure 5 is a perspective view of a metal strap bent preparatory to holding the glass ribbon in place.

Figure 6 is a view corresponding to Figure 3, but showing a modification.

Figure 7 is another view corresponding to Fig ure 3, but showing another modification.

Figure 8 is a diagrammatic view of several lamps embodying our invention and arranged for series operation.

When ordinary incandescent electric lamps are burned in series, the whole string is extinguished upon failure of one of the filaments. When such lamps are designed for street raflway series service using, for example, 30 volt lamps operated 20 in a string with available potential of 600 volts, it has been the practice to place a small piece of oxidized aluminum plate between adjacent portions of the filament leads, and hold said plate in place by means of a ceramic insulator. Upon failure of the filament, and when the entire 600 volts of the line is available at such a point, an arc occurs breaking down the oxide coating on the aluminum plate and maintaining the circuit through other lamps in the series. However, such an arrangement is not entirely satisfactory because it is somewhat uncertain and comparatively expensive.

In accordance with our invention, we have replaced the oxidized aluminum separator by a foraminous insulating sheet or film and the supporting relatively expensive ceramic holder by a relatively cheap small metal strap thereby saving a large proportion of expense of such a cutout device, while at the same time improving the operation of the lamps having such cut-out.

Referring to the drawing in detail, and first considering the embodiment illustrated in Figures 1 to 5, inclusive, there is shown a lamp II provided with a translucent or transparent vitreous or glass envelope l2, to which is sealed a flare tube i3 having leads l4 and I5. The outer end or flaring portion iii of the tube I3 is sealed to the neck or small portion of the bulb l2. Disposed between the leads and outwardly of the press I! is an exhaust tube l8, communicating with theinterior of the envelope through opening IS in the press l1.

Secured to the inner ends of the leads I and I5 is an incandescible filament 2|, which in the present embodiment is shown as coiled. Portions of the leads between the press I! and the filament 2| are disposed parallel and close together, as indicated at 22. Between said parallel closely-spaced lead portions is disposed a suitsection is held in any suitable maner, as by means of metal strap 24, which is bent around both leads and embraces the insulator 23, as shown in Figures 1, 2 and 3. The metal strap 24 may be formed of degassed nickel, stainless steel,

Nichrome, aluminum, nickel-iron alloy, or other similar material.

Although we do not wish to be limited to gas filling, the embodiment of the lamp illustrated is filled with a mixture of 98% argon and 2% nitrogen, by volume, at a pressure of 600 mm. of mercury. After exhausting and filling through the exhaust tube IS, the latter is tipped off as indicated at 25. A conventional type of base 26 is shown cemented to the lamp.

Although we have shown glass cloth 23 held in place by the metal strap 24, which in Figure 3 has its leaves secured together by riveting indicated at 21, yet as an alternative shown in Figure 6, said leaves may be secured together by spot welding 21, or as shown in Figure 7 by crimping indicated at 21 or in any other suitable manner, as will be understood.

As shown in Figure 8, we propose to employ such lamps in series and energized from a source of current indicated at 28. If the lamp ll, for example, fails during operation in series with other lamps H, as by the filament 2| breaking, an arc occurs through its insulator 23 and maintains the circuit through the associated lamps 1 I From the foregoing, it will be seen that we have devised a lamp with an improved cut-out device which maintains circuit continuity under the intended conditions, covering all lamp failures, even those simultaneously containing air and broken filaments, whereby it is particularly adapted for series service, said device not only giving improved operation as compared with the oxidized aluminum and ceramic holder of the prior art, but involving a reduction in total lamp cost, including saving of about 93% of the cost of such prior art cut-out device.

Although preferred embodiments of our invention have been disclosed, it will be understood that modifications may be made within the spirit and scope of the appended claims.

We claim:

1. An incandescent electric lamp for series service comprising an enclosing translucent vitreous envelope, a mount therein including a pair of leads, a filament supported on the inner end portions thereof, said leads closely paralleling each other for a portion of their lengths inside of said envelope, and a thin layer of foraminous heat-resisting insulating material disposed between said parallel lead portions to maintain a. slight spacing thereof, whereby if the filament fails and the total available voltage appears at said leads, an arc occurs therebetween and maintains the circuit.

2. An incandescent electric lamp for series service comprising an enclosin gas-filled glass terial, disposed between envelope, a mount therein including a pair of leads, a filament the ends of which are respectlvely connected to said leads, the latter closely paralleling one another for a Portion of their lengths on the inside of said envelope, and a thin layer of foraminous heat-resisting insulating material disposed between said parallel lead portions to maintain a slight spacing thereof. whereby if the filament fails and the total available voltage appears at said leads, an arc occurs therebetween and maintains the circuit through other lamps if in series therewith.

3. An incandescent electric lamp for series service comprising an enclosing translucent vitreous envelope, a mount therein including a pair of leads, a filament supported on said leads, the latter extending close to one another at one place inside of said envelope, and a thin layer of forminous heat-resisting insulating material, disposed between said closely-spaced lead portions to maintain the spacing thereof, whereby if the lilament fails and the total available voltage appears at said leads, an arc occurs therebetween and maintains the circuit through other lamps if in series therewith.

4. An incandescent electric lamp comprising an enclosing translucent vitreous envelope, a mount therein including a pair of leads, a filament supported on the inner portions thereof, said leads closely paralleling each other for a portion of their lengths inside of said envelope, and a small piece of woven glass ribbon disposed between,

spacing, and held in place with respect to, said parallel lead portions, whereby if the filament fails and the total available voltage appears at said leads, an arc occurs therebetween and maintains the circuit.

5. An incandescent electric lamp for series service comprising an enclosing gas-filled glass envelope, a mount therein including a: pair of leads, a filament supported on said leads, the latter closely paralleling each other for a portion of their lengths inside of said envelope, and a thin layer of foraminous heat-resisting insulating masaid parallel lead portions to maintain the spacing thereof, whereby if the filament fails and thetotal available voltage appears at said leads, an arc occurs therebetween and maintains the circuit.

6. An incandescent electric lamp for seria service comprising an enclosing gas-filled glass envelope, a mount therein including a pair of leads, a filament the ends of which are respectively connected to said leads, the latter closely 5 paralleling one another for a portion of their lengths on the inside of said envelope, and a small piece of woven glass ribbon disposed between, spacing, and held in place with respect to, said parallel lead portions, whereby if the filament fails and the total available voltage appears at said leads, an arc occurs therebetween and maintains the circuit through other lamps if in series therewith.

7. An incandescent electric lamp comprising an enclosing translucent vitreous envelope, a mount therein including a pair of leads, a filament supported on the inner portions thereof, said leads closely paralleling each other for a portion of their lengths inside of said envelope, and a small and the total available voltage appears at said amazon leads, an arc occurs therebetween and maintains the circuit.

8. A cut-out device for a series incandescent electric lamp comprising a piece of woven glass ribbon about wide by V in area and formed from thread about .0015" in diameter, disposed between, spacing, and held in place with respect to parallel lead portions in the envelope of said lamp by a metal strap embracing it and said leads, whereby it the filament of said lamp fails, the total voltage available appears at said leads and an arc occurs therebetween and maintains the circuit through other lamps which may be in series therewith.

- CLAIR MICHAEL RIVELY.

KENNETH G. CROCKER.

amnucas crrnn The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 386,099 Wightman 8: Lemp July 10, 1888 1,024,495 Booth Apr. 30, 1912 1,687,530 Van Horn Oct. 16, 1928 

